Two layers are added to the existing structure: A perforated concrete façade and a screen of glass panels.
The perforated concrete facade wraps the skeleton breaking with its emphatic verticality and replacing it with a more homogenous texture of openings. The materiality of this added layer and its perforations introduce a notion of solid, which underlines the strong presence of the tower in Piraeus. The openings are positioned within a grid by an engine that tends to create bigger windows the higher the floor to accentuate the stunning views over the port of Piraeus and the city of Athens.
In the typical condition, the openings in the concrete façade are occupied by box-type windows composed by two layers of glazing. The box-type windows operate as a functional unit providing a natural ventilation effect. Locally inserted balconies make the space between the two layers of glazing habitable: The exterior layer is pushed outwards and the box-type window splits up in an interior weather barrier and an exterior glass panel, which protects the balconies.
Starting from the balconies, glass panels are spreading over the facade following the logic of the diffusion-limited aggregation (DLA). This algorithm simulates an organic growth based on randomly moving particles (in this case glass panels), which aggregate to clusters.
The two northern facades provide a high number of balconies. These balconies, being joined together by the sprawling glass panels, lead to a very textural character of the glass screen. On the southern facades on the other hand, the original box-type windows prevail, due to their performance in terms of creating natural ventilation. At the same time these two facades are the most representatives and the relatively few exterior glass panels are drawing an expressive figure: The transformed window, which sprawls over the facade, is creating a distinct pattern that reveals the iconic potential of the Piraeus Tower as a landmark within a larger context.
The concrete facade is made out of non load-bearing prefabricated elements. These elements consist of two layers of white concrete with insulation in between, held together by reinforcement. Due to the prefabrication process, the production and the mounting of the elements is very efficient. Furthermore very thin material thicknesses are possible, reducing the weight of the elements, which are clipped to the existing slabs by means of a metal juncture.
The windows are composed of two layers of glazing. In the typical condition these two window panes are both situated within the thickness of the facade and operate as a box-type window with the interior glazing being the actual weather barrier. The increase of temperature between the two layers of glazing produces a natural ventilation effect and thermal buffer: hot air rises through the gap between the exterior glazing and the concrete facade, which in turn evacuates air from the interior of the building.
Where the exterior glazing becomes larger and is placed on the exterior of the facade, the glass panels are held in place by metal beams, which are attached directly to the existing slab. These beams are also carrying the balconies that occur between the glass screen and the concrete facade. To increase the performance of the glass panels, they are reinforced with a DuPont SentryGlas structural interlayer.
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